Sclerosing Therapy for Endometriomas: A Fertility-Friendly Alternative to Surgery

In short: Sclerotherapy is a gentle alternative to surgery for endometriosis cysts on the ovary: the contents of the cyst are drawn out, 95% ethanol is injected for about 10 minutes and then withdrawn, and the cyst gradually shrinks. It suits women who wish to preserve their fertility or for whom surgery is not suitable, and is not used in pregnancy or when a malignant tumour is suspected.

• Endometriosis is a common gynecological condition in which tissue similar to the lining of the uterus grows outside the uterine cavity.
• The most common site for endometriosis is the pelvic organs, especially the ovaries.
• When endometrial implants form on the ovary, they can develop into cysts known as endometriomas, often called “chocolate cysts” because of their dark, thick fluid content.
• Endometriomas are usually firmly attached to the ovarian tissue, so surgical removal can unintentionally take away a significant part of healthy ovary along with the cyst — which may lower the ovarian reserve (a woman’s remaining egg supply).
• Because protecting fertility is so important, doctors and researchers have looked for gentler ways to treat endometriomas without surgery, to help avoid this decline in ovarian reserve.
• One such method is using a sclerosing agent — ethanol — to shrink and manage the cyst.

How does ethanol work on the cyst?

Ethanol works by causing protein denaturation and fibrosis (scarring) of the cyst wall, which helps shrink the endometrioma over time.

How is the procedure performed?

• The fluid inside the cyst is gently aspirated (drained).
• A 95% ethanol solution is then instilled into the empty cyst cavity.
• The ethanol is left in place for about 10 minutes and then aspirated back out.

• The procedure is usually done under ultrasound guidance, with sedation, and antibiotics are often given. Possible risks include pelvic pain, infection or abscess, leakage of ethanol into the pelvis, and temporary effects of absorbed alcohol such as flushing or dizziness.

Why is ethanol the preferred sclerosing agent?

It is generally chosen because of its favorable outcomes and wide availability compared to other agents.

Who may be a good candidate for endometrioma sclerotherapy?

• Women who wish to preserve their fertility and have symptomatic endometriomas
• Women for whom surgery is not advisable or is contraindicated
• Women who have experienced recurrence of an endometrioma after previous surgery

When is this treatment not recommended?

• If malignancy (cancer) is suspected
• If the cyst does not have the typical appearance of an endometrioma on ultrasound — because no tissue sample is taken, a careful scan (and sometimes MRI) is essential to rule out other types of cyst
• If there is an active pelvic infection
• If the patient is pregnant

What are the results of this procedure?

Studies suggest that sclerotherapy preserves ovarian reserve better than surgical removal of the cyst, but the cyst comes back in roughly 10–30% of women (more often when the ethanol is left for only a short time). The evidence comes mainly from small studies, and international guidelines (ESHRE 2022) consider it an option that still needs more research, so your specialist can help explain what to expect in your specific case.

If you have been diagnosed with an endometrioma and are concerned about protecting your fertility, it may help to discuss all your treatment options — including sclerotherapy — with a specialist experienced in fertility-preserving care.

Dr Najeeb Layyous F.R.C.O.G

Consultant Obstetrician, Gynecologist and Infertility Specialist